Propeller Replacement Propeller Dia (In.) 20 in Bore Dia (In.) 1/2 in Number of Blades 4 Pitch (Deg.) 24 Degrees Blade Material Spark Resistant Cast Aluminum Keyway (In.) - Number of Set Screws 2 Rotation CW Facing Discharge Required Motor HP 1/2 Required HP @ Higher RPM - RPM Low - RPM High - Max RPM 1725 CFM @ 0.000-In. SP 4580 CFM @ 0.125-In. SP 3940 CFM @ 0.250-In. SP 3360 CFM @ 0.375-In. SP 2 840 cfm CFM @ 0.500-In. SP 2 325 cfm Blade Height (In.) -